CULTIVATION:

CULTIVATION They are readily cultivated in the yolk sac of developing chick embryo They also grow on mouse fibroblast,HeLa,Hep2,Detroit-6 and other continuous cell lines but tissue cultures are not satisfactory for primary isolation Guinea pigs and mice are useful for the isolation of rickettsiae from patients

RESISTANCE:

RESISTANCE Rickettsiae are readily inactivated by physical and chemical agents They are rapidly destroyed at 56 0 C and at RT when separated from host components. They can be preserved in skimmed milk or a suspending medium containing sucrose, potassium phosphate and glutamate(SPG medium)

Epidemic typhus :

Epidemic typhus Louse borne typhus /classical typhus /gaol fever Epidemic during war and famine reported from all part of the world . Common in Russia and Eastern Europe Typhos = cloud / smoke Typhus =cloudy state of conciousness Incubation period -5-15 days

Epidemic typhus :

Epidemic typhus Starts with fever and chills Rash on 4 th or 5 th day – trunk  limbs(sparing palms and soles ) pt become stuporous and delirious during second week Case fatality rate 40%  with age In those who recover from disease , Rickettsia remain dorment for years in the lymphoid tissue or organs .Reactivation recrudescent typhus (Brill Zinsser disease )

Slide 18:

Mode of transmission Through the bite of infected fleas .when their saliva /faeces rubbed in Through aerosols of dried faeces . Ingestion of food contaminated with rat urine /flea faeces Human infection is a dead end Man to man transmission does not occur .

NEILL-MOOSER REACTION tunica reaction:

NEILL-MOOSER REACTION tunica reaction Animal inoculation test to differentiate R.typhi and R.prowzekii Both are closely similar Blood sample collected from a patient Inoculated intra peritoneally Male guinea pigs Scrotal inflammation Scrotum becomes enlarged () Testes cannot be pushed back into the abdoman because of inflammatory adhesions between the layers of tunica vaginalis

Endemic typhus :

Endemic typhus If test is positivie  R.typhi If test is negative R.prowzekii

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In dried faeces or wool it survives for a year It cannot be destroyed with pasteurisation by the holder method but flash method is effective Lab  Culture - yolk sac of chicken embryo cell cultures Serology – CFT,IFA Isolation of C oxiella from blood, sputum and other clinical specimens possible. But not recommended due to laboratory infection

Trench fever/5 day fever :

Trench fever/5 day fever During the first word war m ore than million cases occurred among soldiers fighting in the trenches in Europe Disease not fatal .Slow course and prolonged convalescence  considerable loss of man power Exclusively a human disease No animal reservoir Causative agent B. quintana / Rochalimaea quintana vector – body louse

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The faeces of lice become infectious 5-10 days after an infectious meal. The lice are unharmed but remain infective through out their life Vertical transmission does not occur in lice Culture B. quintana grows on blood agar –this is the only rickettsiae which can grow on artificial media The disease leads to chronic or latent infection

Oroya fever :

Oroya fever Causative agent: Bartonella . bacilliformis Outbreak of fever killed thousands of workmen in 1870 when the railway line from Lima to Oroya in PERU was built – oroya fever Some of the survivers developed nodular ulcerating skin lesions - Verruga peruvana The common etiology of these two condition established by a Peruvian medical student – Daniel carrion in 1885 who injected himself with the infected material obtained from a case of Verruga peruvana developed oroya fever and died – C arrions diseae

Slide 40:

Daniel carrion

Slide 41:

Clinical features Fever Progressive anaemia – bacterial invasion of erythrocytes Mortality high in untreated cases A late sequele in survivors or in those with asymptomatic infection B. bacilliformis seen inside in RBC and in skin lesions Pleomorphic gram negative rods Motile by a tuft of polar flagella Culture :semisolid agar with rabbit or human blood